Styrene/butadiene diblock copolymer-containing blends that are not an agglomeration and a process for preparation

ABSTRACT

A process for producing a styrene-butadiene diblock copolymer-containing blend that is not an agglomeration, that involves mixing a styrene-butadiene multiblock thermoplastic elastomer solution with a styrene-butadiene diblock copolymer solution. Blends comprising a styrene-butadiene diblock copolymer and a styrene-butadiene multiblock thermoplastic elastomer, which blends are not an agglomeration.

This application is the national stage of International Application No.PCT/US09/52787, filed Aug. 5, 2009, which claims the benefit of U.S.Application No. 61/086234, filed Aug. 5, 2008.

FIELD OF THE DISCLOSURE

The present disclosure relates to specific styrene-butadiene diblockcopolymer-containing blends or compositions that are not anagglomeration, and a process for preparing the blends or compositions.

BACKGROUND OF THE DISCLOSURE

It has been found that solution polymerized styrene-butadiene diblockcopolymers are useful in adhesives and asphalt modification. Thecopolymers are produced in the form of bales having optimum friabilityand grindability. However, the copolymers generally must be ground intogranular form, and have an antiblock applied before use in adhesive andasphalts. Accordingly, it would be advantageous to provide astyrene/butadiene diblock copolymer-containing blend that is not anagglomeration, and a process that would avoid or reduce the need forhaving to grind the product and having an antiblock applied before use,in adhesives and asphalts.

SUMMARY OF THE DISCLOSURE

The present disclosure, in one embodiment, relates to a specific blendsor compositions comprising a styrene-butadiene diblock copolymer and astyrene-butadiene multiblock thermoplastic elastomer. The blends orcompositions are not an agglomeration. The blends or compositions have anumber average molecular weight (M_(n)) of about 40,000 to about 250,000g/mole in one embodiment, and in another embodiment, of about 45,000 toabout 100,000 g/mole, and in yet another embodiment, of about 60,000 toabout 80,000 g/mole.

The present disclosure, in another embodiment, relates to a process forproducing specific styrene-butadiene diblock copolymer-containing blendsthat are not an agglomeration. The process involves blending a solutionof styrene-butadiene diblock copolymer with a solution of astyrene-butadiene multiblock thermoplastic elastomer, and drying theblends.

Furthermore, in one embodiment, with respect to the blends orcompositions herein, it is required that the bound styrene content ofthe styrene-butadiene diblock copolymer differ from the bound styrenecontent of the styrene-butadiene multiblock thermoplastic elastomer.

In another embodiment, the blends or compositions comprise astyrene-butadiene multiblock thermoplastic elastomer that has a numberaverage molecular weight (M_(n)) ranging from about 0.5 to about 2 timesthe number average molecular weight (M_(n)) of the styrene-butadienediblock copolymer.

In another embodiment, the blend or composition comprises astyrene-butadiene multiblock thermoplastic elastomer that both has abound styrene content which differs from the bound styrene content ofthe styrene-butadiene diblock copolymer, and has a number averagemolecular weight ranging from about 0.5 to about 2 times the numberaverage molecular weight of the styrene-butadiene diblock copolymer.

Furthermore, it is required that the blends or compositions herein, nothave been produced either in situ in a process or by a coupling typereaction.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure, in one embodiment, relates to a specific blendsor compositions comprising a styrene-butadiene diblock copolymer and astyrene-butadiene multiblock thermoplastic elastomer. The blends orcompositions are not an agglomeration. In one embodiment, the blends orcompositions comprising a styrene-butadiene diblock copolymer and astyrene-butadiene multiblock thermoplastic elastomer comprise at least95% styrene-butadiene copolymer, and in another embodiment, comprise atleast 95% to 100% styrene-butadiene copolymer.

The present disclosure, in another embodiment, relates to a process forproducing specific styrene-butadiene diblock copolymer-containing blendsthat are not an agglomeration. The process involves blending a solutionof styrene-butadiene diblock copolymer with a solution of astyrene-butadiene multiblock thermoplastic elastomer, and drying theblends. The diblock copolymer may have a number average molecular(M_(n)) of about 40,000 to about 250,000, and in another embodiment, ofabout 45,000 to about 100,000, and in another embodiment, of about60,000 to about 80,000 g/mole. The multiblock thermoplastic elastomermay have a number average molecular weight (M_(n)) of about 40,000 toabout 250,000 g/mole in one embodiment, and in another embodiment ofabout 45,000 to about 100,000 g/mole, and in another embodiment, fromabout 60,000 to about 80,000 g/mole.

Furthermore, in one embodiment, with respect to the blends orcompositions, and the process herein, it is required that the boundstyrene content of the styrene-butadiene diblock copolymer differ fromthe bound styrene content of the styrene-butadiene multiblockthermoplastic elastomer. In one embodiment, the bound styrene content ofthe diblock copolymer differs from the bound styrene content of themultiblock thermoplastic elastomer by any amount. In another embodiment,the difference in bound styrene contents is greater than about 2%, andin another embodiment, the difference is greater than about 10%, and inyet another embodiment, the difference is greater than about 20%. In oneembodiment, the bound styrene content of the styrene-butadiene diblockcopolymer is less than 50%, and the bound styrene content of thestyrene-butadiene multiblock thermoplastic elastomer is also less than50%.

In another embodiment, the blends or compositions, and the process,comprise a styrene-butadiene multiblock thermoplastic elastomer that hasa number average molecular weight (M_(n)) ranging from about 0.5 toabout 2 times the number average molecular weight (M_(n)) of thestyrene-butadiene diblock copolymer.

In another embodiment, the blend or composition and the process,comprises a styrene-butadiene multiblock thermoplastic elastomer thatboth has a bound styrene content which differs from the bound styrenecontent of the styrene-butadiene diblock copolymer, and has a numberaverage molecular weight ranging from about 0.5 to about 2 times thenumber average molecular weight of the styrene-butadiene diblockcopolymer.

Furthermore, it is required that the blends or compositions herein, nothave been produced either in situ in a process or by a coupling typereaction.

In more detail, the styrene-butadiene diblock copolymer of the blend orcomposition or used in the process, is characterized by having a boundstyrene content, in one embodiment, of about 5% to about 60% based onthe copolymer, and has a block styrene content in one embodiment, ofabout 5% to about 60%, based on the copolymer, and in anotherembodiment, from about 10% to about 45%; and has a number averagemolecular weight (M_(n)) in one embodiment, of about 40,000 g/mole toabout 250,000 g/mole, and in another embodiment, of about 45,000 g/moleto about 100,000 g/mole and in yet another embodiment, of about 60,000to about 80,000 g/mole. An example of the styrene-butadiene diblockcopolymer of the present blend or composition is Stereon 210 copolymer(Stereon is a registered trademark of Firestone Polymers, Akron, Ohio).

The styrene-butadiene multiblock thermoplastic elastomer utilized in thepresent blend or composition, and used in the process, is characterizedby having a bound styrene content, in one embodiment, of about 20% toabout 60%, based on the elastomer; and has a block styrene content ofabout 20% to about 60%, based on the elastomer, and has a structuralaspect of (SB)_(x), (SBS)_(x) or (BSB)_(x) where the subscript “x,”refers to the number of units. The styrene-butadiene elastomers have anumber average molecular weight (M_(n)) in one embodiment, of about40,000 to about 250,000 g/mole, and in another embodiment, of about45,000 to about 100,000 g/mole, and in another embodiment, of about60,000 to about 80,000 g/mole. An example of the styrene-butadieneelastomer of the present blend or composition is Stereon 842A elastomer(Stereon is a registered trademark of Firestone Polymers of Akron,Ohio).

In another embodiment, the blend or composition comprises, and theprocess utilizes, a styrene-butadiene diblock copolymer that has a boundstyrene content of about 5% to about 60% based on the copolymer, and ablock styrene content of about 5% to about 60% based on the copolymer,and a number average molecular weight (M_(n)) in one embodiment, ofabout 40,000 to about 250,000 g/mole, and in another embodiment, ofabout 45,000 to about 100,000 g/mole, and in another embodiment, ofabout 60,000 to about 80,000 g/mole, and a styrene-butadiene multiblockthermoplastic elastomer that has a bound styrene content of about 20% toabout 60% based on the elastomer, a block styrene content of about 20%to about 60% based on the elastomer, and a number average molecularweight (M_(n)) in one embodiment, of about 40,000 to about 250,000g/mole, and in another embodiment, of about 45,000 to about 100,000g/mole, and in yet another embodiment of about 60,000 to about 80,000g/mole.

In another embodiment, the blends or compositions, and the process,herein utilize a styrene-butadiene diblock copolymer having a blockstyrene content that differs from the block styrene content of thestyrene-butadiene multiblock thermoplastic elastomer.

In another embodiment, the blends or compositions, and the process,herein utilize a styrene-butadiene multiblock thermoplastic elastomerhaving a bound styrene content that exceeds the bound styrene content ofthe styrene-butadiene diblock copolymer.

In another embodiment, the blends or compositions, and the process,herein involve the presence of a styrene-butadiene diblock copolymer inan amount of from about 60% to about 90% and the presence of astyrene-butadiene multiblock thermoplastic elastomer in an amount offrom about 10% to about 40%, the amounts based on total polymer.

In another embodiment, the blends or compositions, and the process,herein utilize a styrene-butadiene multiblock thermoplastic elastomerthat has a number average molecular weight (M_(n)) which is about equalto the number average molecular weight (M_(n)) of the styrene-butadienediblock copolymer.

In another embodiment, the blends or compositions, or the process,herein involve the presence of a styrene-butadiene diblock copolymer inan amount ranging from greater than zero to less than 100% based ontotal polymer, and the presence of a styrene-butadiene multiblockthermoplastic elastomer in an amount ranging from about greater thanzero to about 100% based on total polymer.

The process for preparing a styrene-butadiene diblockcopolymer-comprising blends or composition that is not an agglomeration,involves the following operations.

A solution of the styrene-butadiene diblock copolymer is prepared, forexample, by dissolving the styrene-butadiene diblock copolymer in anysuitable solvent. Exemplary of suitable solvents are hexanes,cyclohexane, toluene, mixtures thereof, and the like.

A solution of the styrene-butadiene multiblock thermoplastic elastomeris prepared, for example, by dissolving the elastomer in any suitablesolvent. Exemplary of suitable solvents are hexanes, cyclohexane,toluene, mixtures thereof, and the like.

The solutions of the styrene-butadiene diblock copolymer and thestyrene-butadiene multiblock thermoplastic elastomer may be preparedseparately, or alternatively, a blend of the styrene-butadiene diblockcopolymer and the styrene-butadiene multiblock thermoplastic elastomermay be prepared, which blend is then dissolved in solvent.

The solution of the styrene-butadiene diblock copolymer and the solutionof the styrene-butadiene multiblock thermoplastic elastomer are mixed ata temperature that causes the mixture to be pumpable.

The mixture of styrene-butadiene diblock copolymer solution andstyrene-butadiene multiblock thermoplastic elastomer solution, is mixedto produce a solution (or cement) of the blend.

The resulting solution or cement is then dried to remove solvent to forma dry polymer blend. Any known procedure may be utilized to dry thecement and remove the solvent. For example, suitable drying methodsinclude direct drying, steam desolventizing, and the like.

The dried polymer blends resulting from the process are notagglomerations.

The following examples are presented to illustrate the presentdisclosure and to assist one of ordinary skill in making and using thesame. The examples are not intended in any way to otherwise limit thescope of the disclosure.

EXAMPLES

In determining various properties mentioned herein, the following testprocedures were utilized.

Number Average Molecular Weight (M_(n))—

The number-average molecular weight (M_(n)) and molecular weightdistribution of a polymer were measured by gel permeation chromatography(GPC), using a differential refractive index (RI), and, as a solvent,tetrahydrofuran (THF). The molecular weights were expressed in terms ofpolystyrene, i.e., they were obtained by conversion into polystyrenemolecular weight, using monodisperse polystyrene as a standard.

Bound Styrene—

The microstructure of the butadiene moiety of a styrene-butadienecopolymer was determined by the infrared ray method (D. Morero et. Al.,Chem. Ind., 41, 758 (1959)). The amount of bound styrene was determinedfrom a calibration curve obtained by the infrared method based on theabsorption of a phenyl group at 3026 cm⁻¹.

Block Styrene—

The block styrene was determined by the osmium oxidative degradationmethod as described in I. M. Kolthoff, et al, J. Polym. Sci., 1, 429(1946). The partial digestion of a styrene-butadiene copolymer (0.5 gramsample) was effected by reaction with osmium tetroxide and t-butylhydroperoxide. The remaining precipitate (block styrene) was isolatedand weighed. The final block styrene was expressed as a weight percentof block styrene by difference from the total polymer amount used.

Example 1

A blend or composition comprising 76% Stereon 210 styrene-butadienediblock copolymer, and 24% Stereon 842A styrene-butadiene multiblockthermoplastic elastomer was prepared. The Stereon 210 co-polymer has abound styrene content of 25% and a number average molecular weight(M_(n)) of 68,000 g/mole; and the Stereon 842A elastomer has a boundstyrene content of 44.5 weight %, and a (M_(n)) of 67,000 g/mole. TheStereon 210 copolymer, and the Stereon 842A elastomer were eachdissolved in hexanes, and both polymer solutions or cements wereprepared at 15% total solids.

In preparing the blend, 611 lbs. of the Stereon 210 cement, and 193 lbs.of the Stereon 842A cement were transferred to a blend tank. Thecontents of the blend tank were mechanically mixed, using an agitator,at a temperature of about 125° to 150° F., for a period of about 2hours, such that the resultant mixture was pumpable. The hexane wasremoved from a portion of the total cement by steam desolventization,followed by drying to remove excess water.

As a result of the process, there was obtained about 100 lbs. of theblend, in the form of crumb. Moreover, the resultant crumb was not anagglomeration.

It should be clearly understood that the forms of the invention hereindescribed are illustrative only and are not intended to limit the scopeof the invention. The present invention includes all modificationsfalling within the scope of the following claims.

1. A process for producing a styrene-butadiene diblockcopolymer-comprising blend that is not an agglomeration comprisingmixing a first solution of the styrene-butadiene diblock copolymer witha second solution of a styrene-butadiene multiblock thermoplasticelastomer, and drying the resultant mixture, wherein thestyrene-butadiene diblock copolymer has a bound styrene content of about5% to about 60% based on the copolymer, and a block styrene content ofabout 5% to about 60% based on the copolymer, and a number averagemolecular weight (M_(n)) of about 40,000 to about 250,000 g/mole, andthe styrene-butadiene multiblock thermoplastic elastomer has a boundstyrene content of about 20% to about 60% based on the elastomer, ablock styrene content of about 20% to about 60% based on the elastomer,and a number average molecular weight (M_(n)) of about 40,000 to about250,000 g/mole.
 2. The process of claim 1 wherein the first and secondsolutions are prepared separately.
 3. The process of claim 1 wherein thestyrene-butadiene diblock copolymer is present in an amount of fromabout 60% to about 90%, and the styrene-butadiene multiblockthermoplastic elastomer is present in an amount of from about 10% toabout 40%.
 4. The process of claim 1 wherein the styrene-butadienediblock copolymer has a bound styrene content of about 5% to about 60%based on the copolymer, and a block styrene content of about 5% to about60% based on the copolymer, and a number average molecular weight(M_(n)) of about 40,000 to about 250,000 g/mole, and wherein thestyrene-butadiene multiblock thermoplastic elastomer has a bound styrenecontent of about 20% to about 60% based on the elastomer, a blockstyrene content of about 20% to about 60% based on the elastomer, and anumber average molecular weight (M_(n)) of about 40,000 to about 250,000g/mole.
 5. The process of claim 1 wherein the bound styrene content ofthe diblock copolymer differs from the bound styrene content of theelastomer.
 6. The process of claim 1 wherein the block styrene contentof the diblock copolymer differs from the block styrene content of theelastomer.
 7. The process of claim 1 wherein the number averagemolecular weight (M_(n)) of the elastomer ranges from about 0.1 to about2 times the number average molecular molecular weight (M_(n)) of thediblock copolymer.
 8. A blend comprising a styrene-butadiene diblockcopolymer and a styrene-butadiene multiblock thermoplastic elastomer,which blend is not an agglomeration, and wherein the bound styrenecontent of the diblock copolymer differs from the bound styrene contentof the elastomer, and wherein the number average molecular weight(M_(n)) of the blend ranges from about 40,000 to about 250,000 g/mole.9. The blend of claim 8 wherein the number average molecular weight(M_(n)) of the thermoplastic elastomer ranges from about 0.5 to about 2times the number average molecular weight (M_(n)) of the diblockcopolymer.
 10. The blend of claim 8 wherein the bound styrene content ofthe thermoplastic elastomer exceeds the bound styrene content of thediblock copolymer.
 11. The blend of claim 8 wherein thestyrene-butadiene diblock copolymer has a bound styrene content of about5% to about 60% based on the copolymer, a block styrene content of about5% to about 60% based on the copolymer, and a number average molecularweight (M_(n)) of about 40,000 to about 250,000 g/mole, and thestyrene-butadiene multiblock thermoplastic elastomer has a bound styrenecontent of about 20% to about 60% based on the elastomer, a blockstyrene content of about 20% to about 60% based on the elastomer, and anumber average molecular weight (M_(n)) of about 40,000 to about 250,000g/mole.
 12. The blend of claim 8 wherein the styrene-butadiene diblockcopolymer is present in an mount of from about 60% to about 90%, and thestyrene-butadiene multiblock thermoplastic elastomer is present in anamount of from about 10% to about 40%.
 13. The blend of claims 8 notbeing produced in situ in a process.
 14. The blend of claim 8 not havingbeen produced by a coupling type reaction.
 15. A blend comprising astyrene-butadiene diblock copolymer and a styrene-butadiene multiblockthermoplastic elastomer, which blend is not an agglomeration, andwherein the number average molecular weight (M_(n)) of thestyrene-butadiene multiblock thermoplastic elastomer ranges from about0.5 to about 2 times the number average molecular weight (M_(n)) of thestyrene-butadiene diblock copolymer.
 16. The blend of claim 15 whereinthe number average molecular weight (M_(n)) of the elastomer is aboutequal to the number average molecular weight (M_(n)) of the diblockcopolymer.
 17. The blend of claim 15 wherein the styrene-butadienediblock copolymer has a bound styrene content of about 5% to about 60%based on the copolymer, a block styrene content of about 5% to about 60%based on the copolymer, and a number average molecular weight (M_(n)) ofabout 40,000 to about 250,000 g/mole and the styrene-butadienemultiblock thermoplastic elastomer has a bound styrene content of about20% to about 60% based on the elastomer, a block styrene content ofabout 20% to about 60% based on the elastomer, and a number averagemolecular weight (M_(n)) of about 40,000 to about 250,000 g/mole. 18.The blend of claim 15 wherein the styrene-butadiene diblock copolymer ispresent in an amount of from about 60% to about 90%, and thestyrene-butadiene multiblock thermoplastic elastomer is present in anamount of from about 10% to about 40%.
 19. The blend of claim 15 nothaving been produced in situ in a process.
 20. The blend of claim 15 nothaving been produced by a coupling type reaction.
 21. The process ofclaim 1 wherein the number average molecular weight (M_(n)) of thestyrene-butadiene diblock copolymer is from about 60,000 to about 80,000g/mole.
 22. The process of claim 1 wherein the number average molecularweight (M_(n)) of the styrene-butadiene thermoplastic elastomer is fromabout 60,000 to about 80,000 g/mole.
 23. A blend produced in accordanceto the process of claim
 1. 24. The blend of claim 23 wherein the boundstyrene content of the diblock copolymer differs from the bound styrenecontent of the elastomer by an amount greater than at least about 2%.25. A composition comprising a styrene-butadiene diblock copolymer and astyrene-butadiene multiblock thermoplastic elastomer, which compositionis not an agglomeration, and wherein the bound styrene content of thediblock copolymer differs from the bound styrene content of theelastomer, and wherein the number average molecular weight (M_(n)) ofthe composition is from about 40,000 to about 250,000 g/mole, andwherein the composition comprises at least 95% styrene-butadienecopolymer.